Reigning champion Sebastien Ogier took charge of the Rally de Portugal on Saturday to establish a 38-second lead heading into the final day.
The Frenchman led by less than three seconds going into the afternoon repeat loop but turned the screw on his rivals in emphatic fashion with victory on all three stages at the wheel of the Volkswagen Polo R WRC.
M-Sport Ford's Mikko Hirvonen, who led the way after Friday's running, could not compete with Ogier's afternoon surge as he struggled with grip issues that saw him lose huge amounts of time on stages 11, 12 and 13.
Hirvonen will hope his tyre issues will not again prove troublesome on Sunday, with less than a minute separating him from the third-placed Citroen of Mads Ostberg.
The Hyundai of Dani Sordo is running fourth, one minute and 46 seconds off the outright lead and with a near three-minute gap to the chasing Ford of Henning Solberg.
Andreas Mikkelsen is sixth ahead of Thierry Neuville, Martin Prokop, Juho Hanninen and Nasser Al-Attiyah.
M-Sport Ford's Ott Tanak provided the biggest drama of Saturday's running when he crashed out of third place on stage 10, his Fiesta coming to a rest in the middle of the road and forcing the stage to be neutralised.